Elevator control system

ABSTRACT

An improved elevator control system for maintaining a properly controlled interval between a plurality of elevator cars. The system includes means for detecting the time interval or spatial interval between a preceding elevator car, an intermediate elevator car and a succeeding elevator car. When the interval between the preceding and intermediate elevator cars is more than the interval between the intermediate and succeeding elevator cars, the intermediate elevator car is accelerated, while when the former interval is less than the latter interval, the preseding or succeeding elevator car is accelerated for maintaining a reasonable interval between these elevator cars.

Hirasawa et a1.

[ ELEVATOR CONTROL SYSTEM [75] Inventors: Kotaro Hirasawa; KoichiKawatake,

both of Hitachi; Tatsuo lwasaka, Katsuta, all of Japan [73] Assignee:Hitachi, Ltd., Tokyo, Japan [22] Filed: June 25, 1971 [21] Appl. No.:156,866

[30] Foreign Application Priority Data July 1, 1970 Japan 45-56938 July1, 1970 Japan 45-56939 July 10, 1970 Japan .J; 45-59918 July 20, 1970Japan 45-62847 [52] US. Cl 187/29 R [51] Int. Cl B66b 1/18 [58] Field ofSearch 187/29 [56] References Cited I UNITED STATES PATENTS 3,443,6685/1969 Hall et a1. 187/29 MIN/MUM SELECTOR Lusti 187/29 PrimaryExaminer-Robert K. Schaefer Assistant ExaminerW. E. Duncanson, Jr.Attorney, Agent, or FirmCraig & Antonelli [5 7 ABSTRACT An improvedelevator control system for maintaining a properly controlled intervalbetween a plurality of elevator cars. The system includes means fordetecting the time interval or spatial interval between a precedingelevator car, an intermediate elevator car and a succeeding elevatorcar. When the interval between the preceding and intermediate elevatorcars is more than the interval between the'intermediate and succeedingelevator cars, the intermediate elevator car is accelerated, while whenthe former interval is less than the latter interval, the preseding orsucceeding elevator car is accelerated for maintaining a reasonableinterval between these elevator cars.

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INVENTORS KOTARO IWASAKAI K Id-H KAwATAKEmd TATSUO IWASAKA BY aaiswawwHum ATTORNEYS This invention relates to an elevator control system andmore particularly to improvements in an elevator control system forcontrolling the operation of a plurality of elevator cars servicing aplurality of service floor landings.

In a building in which a plurality of elevator cars are in paralleloperation for servicing a plurality of service floor landings, theelevator cars must be prevented from bunching, namely, servicingtogether without any interval therebetween. In other words, it isnecessary to maintain a suitable interval between the elevator cars. Theintervals between these elevator cars need not be equal to each otherand are desirably such that the passengers in a plurality of elevatorhalls wait an equal period of time. I

Reasonable intervals between servicing elevator cars may be obtainedbyaccelerating at least one of the elevator cars on the basis ofinformation including, the intervals between the elevator cars, the hallcalls originating from the floors, etc. The acceleration of a specificelevator car may be attained by limiting its response to forward hallcalls originating from the floors lying within a predetermined range,from the position of a specific elevator car indicated by a positionsignal (which will be described in detail later), thereby apparentlyadvancing the position of the elevator car, or preventing the elevatorcar from responding to such forward hall calls until a predeterminedcondition is satisfied.

The position signal above described may represent the floor number orspace, but it is preferable for practical purposes that the positionsignal represents the floor number. When theposition signal indicatesthe floor number, it represents the actual position of the elevator carand is thus called a physical position signal. When one of the elevatorcars is at rest at a floor, the position signal may represent the floorat which it is at rest. In this case, this floor coincides with thephysical position of the elevator car. When the elevator car is moving,the position signal may represent a floor which is forward relative tothe physical position of the elevator car. For example, such a floor maybe the fourth floor when the elevator car is moving past the third floorat a low speed, or the fifth floor when the elevator car. is moving pastthe third floor at a medium speed, or the sixth floor when the elevatorcar is moving past the third floor at a high speed. The same applies tothe position signal representing the space.

In a typical elevator control, an elevator car responds to up hall callsfrom the upper floors when it is moving upward and responds to down hallcalls from the lower floors when it is moving downward. Therefore, whenthe first floor is the dispatching floor (bottom terminal) for theelevator cars, each elevator car responds first to an up call from thebottom terminal and then responds successively to up calls from theupper floors, and after arriving at the top terminal floor, respondsfirst to a call from the top terminal floor and then respondssuccessively to down calls from the lower floors. Thus, when a certainfloor is taken as a reference floor, the floors lying forward of thereference floor in the moving direction of the elevator car are calledforward floors and the hall calls from such floors are called forwardhall calls, while the floors lying behind the reference floor in themoving direction of the elevator car are called back floors and the hallcalls from such floors are called back hall calls. For example, when thefifth floor is taken as a reference floor and the elevator car is movingupward, the up call from the sixth floor is a forward hall call and theup call from the third floor is a back hall call. When the elevator caris moving downward,

the down call from the sixth floor is a back hall call and the down callfrom the third floor is a forward hall call.

The elevator car responds commonly to forward hall calls from the floorslying forward of the position represented by the position signal, butwhen the elevator car is arranged so as not to respond to forward hallcalls from the floors lying within a specific range, this elevator caris apparently advanced in its position and its movement is accelerated.In this description, the nearest floor to which the elevator car canactually respond is called a provisional position. Thus,'the provisionalposition coincides with the physical position representeby the positionsignal when no limitation is applied to the forward hall calls, whilethe provisional position is ahead of the physical position when theelevator car is apparently advanced in its position. On the other hand,the provisional position is not definitely determined when the elevatorcar is arranged so as not to respond to all the hall calls includingthose from the floors lying within the specific range until apredetermined condition is eliminated.

In the arrangement in which means for accelerating the elevator cars areprovided for apparently advancing the position of the elevator cars overa predetermined range, the service zone to which each individualelevator car should respond can be definitely determined. However, theservice zone to be served by each individual elevator car is indistinctwhen arrangement is made so that at least one suitable elevator car isprevented from responding to all the hall calls until disorderlymovement of the elevator cars is eliminated. The former arrangementrequires means for determining whether or not each individual elevatorcar should respond to the hall calls from the floor. In the latterarrangement, control means for controlling the elevator cars as towhether or not each individual elevator car should respond to all thehall calls can be simplified in structure, but it is necessary todetermine the elevator car which should respond to a hall calloriginating from a specific floor.

It is therefore an object of the present invention to provide anelevator control system for controlling the operating condition ofelevator cars depending on the traffic so as to operate the elevatorcars in suitably spaced relation from each other thereby tosubstantially equalize the waiting time for the passengers waiting inthe elevator halls.

Another object of the present invention is to provide an elevatorcontrol system which eliminates undesirable bunching of continuouslymoving elevator cars so as to improve the operating efficiency.

A further object of the present invention is to provide an elevatorcontrol system having means for detecting the disorderly movement ofelevator cars so as to prevent at least one of the elevator cars fromresponding to all the hall calls in the event of occurrence of suchdisorderly movement, means are provided for immediately selecting one ofthe elevator cars which can respond to a hall call in response to theregistration of such a hall call.

One feature of the present invention resides in the fact that, when theinterval between a preceding elevator car and a succeeding elevator carexceeds a predetermined limit, the succeeding elevator car isaccelerated to maintain a reasonable interval therebetween.

Another feature of the present invention resides in the fact that, whenthe interval between a preceding elevator car and an intermediateelevator car among three elevator cars exceeds the interval between asucceeding elevator car and the intermediate elevator car by more than apredetermined limit, the intermediate elevator car is accelerated tomaintain a reasonable interval between it and the preceding elevatorcar, while when the interval between the succeeding elevator car and theintermediate elevator car exceeds the interval between the precedingelevator car and the intermediate elevator car by more than thepredetermined limit, the preceding elevator car or succeeding elevatorcar is accelerated to maintain a reasonable interval between it and theintermediate elevator car.

A further feature of the present invention resides in the fact that anelevator car applied with an acceleration command signal does notrespond to any forward or back hall calls during the period of time inwhich the acceleration command signal is continuously applied.

For a full understanding of the nature and objects of the presentinvention, reference should be had to the following detailed descriptiontaken in conjunction with the accompanying drawings, in which:

FIGS. la and 1b are schematic diagrams showing the running state of aplurality of elevator cars;

FIG. 2 is a block diagram showing the structure of an elevator controlsystem embodying the present inventron;

FIG. 3a is a block diagram showing the structure of one form of anacceleration signal generator;

FIGS. 3b, 3c and 3d are diagrammatic views showing varrious runningstates of the elevator cars;

FIG. 4 is a circuit diagram showing the structure of one form of aposition detector;

FIG. 5 is a chart illustrating the operation of the position detectorshown in FIG. 4;

FIG. 6 is a circuit diagram showing the structure of one form of aspatial distance calculator;

FIGS. 7a, 7b and 7c are diagrammatic views illustrating the operation ofthe spatial distance calculator shown in FIG. 6;

FIG. 8 is a circuit diagram showing the structure of one form of a timedistance calculator;

' FIG. 9 is a block diagram showing the structure of one form of controlmeans used in the acceleration signal generator for controlling theoperation of the elevator cars by the acceleration signal;

FIG. 10 is a circuit diagram showing in detail in the structure of oneform of an interval calculating, order, selector;

FIG. 11 is a circuit diagram showing in detail the structure of one formof an interval calculating commander;

FIG. 12 is a circuit diagram showing in detail the structure of one formof means for detecting a hall call and the interval between the elevatorcars;

FIG. 13 is a circuit diagram showing the structure of one form of meansfor generating a voltage in response to a specific hall call;

FIG. 14 is a circuit diagram showing the structure of one form of meansfor calculating the distance between the elevator cars and a specificfloor;

FIG. 15 is a circuit diagram showing in detail the structure of one formof a-minimum selector; and

FIGS. 16 and 17 are block diagrams showing partial modifications of thesystem according to the present invention.

Referring to FIGS. la and 1b, the present invention will be describedwith reference to an elevator system in which three elevator cars A, Band C are provided in a building having 10 floors designated by F l toF10. The physical positions of the elevator cars A, B and C aredesignated by 1U to 9U when they move upward and by 10D to 2D when theymove downward.

There are various methods for detecting the disorderly movement of theseelevator cars and correcting the disorder to obtain a reasonableinterval therebetween. According to one method in which two out of thethree elevator cars are considered, the position signals representingthe physical positions of the two elevator cars are generated and thepreceding elevator car is accelerated when the difference between theposition signal representing the position of the preceding elevator carand the position signal representing the position of the succeedingelevator car becomes smaller than a predetermined limit. On the otherhand, the succeeding elevator car is accelerated when the differencebetween theposition signals exceeds the predetermined limit.

According to another method in which all of the three elevator cars areconsidered, the intermediate elevator car is accelerated when theinterval between the preceding and intermediate elevator cars exceedsthe interval between the intermediate and succeeding elevator cars. Onthe other hand, the succeeding or preceding elevator car is acceleratedwhen the interval between the succeeding and intermediate elevator carsexceeds the interval between the intermediate and preceding elevatorcars.

According to a further method in which each individual elevator car isconsidered, each individual elevator car is accelerated when it isdelayed by a predetermined time from a predetermined running schedule.vEach individual elevator car is accelerated when disorder occurs in thearrival of the elevator cars at different floors.

Further, in addition to the spatial distance between the elevator carsas described above, the concept of the time distance taking intoconsideration the function of time associated with the number ofstoppages of the elevator cars may be introduced for effectivelycontrolling the operation of the elevator cars.

FIG. 2 is a block diagram showing the structure of an embodiment of thepresent invention in which the three elevators cars servicing thebuilding having 10 floors are adapted to be controlled by the secondmethod above described.

Position detectors DA, DB and DC for the respective elevator cars A, Band C generate position signals FA, FE and FC representing the physicalpositions of the respective elevator cars A, B and C. A hall callregister I-ICR stores hall calls l-IClU (up hall call from the firstfloor) to I-IC9U and I-IC10D (down hall call from the tenth floor) toHC2D. The hall call register l-ICR is reset by a reset signal REl uponarrival of the elevator

1. An elevator control system for controlling a plurality of elevatorcars servicing a plurality of service floor landings comprising:interval detecting means provided for each elevator car for detectingthe interval between each elevator car and a preceding elevator carwhich is positioned ahead of said elevator car and for generating acorresponding interval signal representing said interval, means forproviding a signal representing a desirable interval between anyadjacent two of said elevator cars, comparator means provided for eachelevator car for comparing the interval signal generated by thecorresponding interval detecting means with said signal representingsaid desirable interval and to produce an output signal when saidinterval exceeds a predetermined value over said desirable interval,accelerating means provided for each car and responsive to the outputsignal produced by said comparator means for accelerating the elevatorcar associated with said comparator means, and said interval detectingmeans comprising means for detecting the spatial distance between eachelevator car and the preceding elevator car, means for detecting thetime distance related to the number of stoppages expected for eachelevator car, and means for generating a time interval signal which isproportional to the sum of said spatial distance and said time distance.2. An elevator control system for controlling a plurality of elevatorcars servicing a plurality of service floor landings comprising:interval detecting means provided for each elevator car for detectingthe interval between each elevator car and a preceding elevator carwhich is positioned head of said elevator car and for generating acorresponding interval signal representing said interval, means forproviding a signal representing a desirable interval between anyadjacent two of said elevator cars, comparator means provided for eachelevator car for comparing the interval signal generated by thecorresponding interval detecting means with said signal representingsaid desirable interval and to produce an output siGnal when saidinterval exceeds a predetermined value over said desirable interval,accelerating means provided for each car and responsive to the outputsignal produced by said comparator means for accelerating the elevatorcar associated with said comparator means, and said interval detectingmeans comprising means for detecting the spatial distance between eachelevator car and the preceding elevator car, means for detecting thetime distance related to the number of stoppages expected for eachelevator car while it moves through said spatial distance, and means fordetecting the time interval which is the sum of said spatial distanceand said time distance.
 3. An elevator control system for controlling aplurality of elevator cars servicing a plurality of service floorlandings comprising: interval detecting means provided for each elevatorcar for detecting the interval between each elevator car and a precedingelevator car which is positioned ahead of said elevator car and forgenerating a corresponding interval signal representing said interval,means for providing a signal representing a desirable interval betweenany adjacent two of said elevator cars, comparator means provided foreach elevator car for comparing the interval signal generated by thecorresponding interval detecting means with said signal representingsaid desirable interval and to produce an output signal when saidinterval exceeds a predetermined value over said desirable interval,accelerating means provided for each car and responsive to the outputsignal produced by said comparator means for accelerating the elevatorcar associated with said comparator means, and means for selecting,among the elevator cars that can respond to a hall call, the one nearestto the floor from which the hall call is originated and registered andfor causing the selected car to respond to said hall call, andadditional means responsive to the output from said interval detectingmeans for preventing each elevator car from responding to all of thehall calls.
 4. An elevator control system as claimed in claim 3,including means for displaying at a floor from which a hall calloriginates the indication of the selected elevator car responding to thehall call.
 5. An elevator control system for controlling a plurality ofelevator cars servicing a plurality of service floor landings comprisingposition detecting means for detecting the positions of the respectivecars, hall call selecting means for selecting hall calls for service oneat a time in the order received, interval detecting means responsive tosaid position detecting means and said hall call selecting means fordetecting the backward interval between a specific floor providing aselected hall call and each of the elevator cars, minimum intervalselector means for selecting the minimum of a plurality of backwardintervals, gating means for selectively connecting said intervaldetecting means to said minimum interval selector means, accelerationsignal generator means for generating respective acceleration signals tocontrol movement of said elevator cars, said acceleration signals beingapplied to said gating means when generated to inhibit application ofthe backward interval associated with a particular elevator car to saidminimum interval selector means, and elevator car control means foractuating that elevator car designated by the output of said minimuminterval selector means to respond to said selected hall call.
 6. Anelevator control system as defined in claim 5 wherein said hall callselecting means includes a hall call register for storing received hallcalls and an interval calculating order selector for selecting hallcalls from said hall call register one at a time in the order received.7. An elevator control system as defined in claim 6 wherein saidinterval detecting means includes an individual interval detector foreach elevator car connected to receive the output of said intervalcalculating Order selector and said position detecting means includes aposition detector for each elevator car having its output connected toan associated interval detector.
 8. An elevator control system asdefined in claim 7 wherein said gating means includes a first set ofgates each connected to one of said interval detectors and a second setof gates connected to said first set of gates and said minimum selectormeans, said acceleration signals being applied to said second set ofgates, and further including interval calculating commander meansresponsive to said interval calculating order selector for actuatingsaid first and second sets of gates in timed sequence.
 9. An elevatorcontrol system as defined in claim 8 wherein said acceleration signalgenerator means includes further interval detecting means responsive tosaid position detecting means for detecting the interval between apreceding elevator car and a succeeding elevator car, and acceleratingmeans responsive to the output from said further interval detectingmeans for accelerating the succeeding elevator car when the intervalbetween the elevator cars exceeds a predetermined value.
 10. An elevatorcontrol system as defined in claim 9 wherein said further intervaldetecting means includes means for detecting the spatial distancebetween the preceding elevator car and the succeeding elevator car,means for detecting the time distance related to the number ofinternally initiated stoppages expected for the succeeding elevator carand means for generating a time interval signal which is proportional tothe sum of said spatial distance and said time distance.
 11. An elevatorcontrol system for controlling at least three elevator cars servicing aplurality of service floor landings comprising: first interval detectingmeans for detecting a first interval between each elevator car andpreceding elevator car which is positioned ahead of said each elevatorcar and for generating a first interval signal representing said firstinterval, second interval detecting means for detecting a secondinterval between each elevator car and the elevator car which issucceeding said elevator car and for generating a second interval signalrepresenting said second interval, comparator means provided for eachelevator car to compare the first interval signal with the secondinterval signal with respect to each elevator car and to produce anoutput signal when said first interval signal exceeds by a predeterminedvalue said second interval signal, and means responsive to said outputsignal produced by said comparator means for preventing the elevator carcorresponding to said comparator means from responding hall calls. 12.An elevator control system as claimed in claim 11, in which said firstinterval detecting means detects the spatial distance between eachelevator car and the preceding elevator car, and said second intervaldetecting means detects the spatial distance between each elevator carand the succeeding elevator car.
 13. An elevator control system asclaimed in claim 11, in which said first interval detecting meansdetects the time interval which is the sum of the spatial distancebetween each elevator car and the preceeding elevator car and the timedistance related to the number of stoppages expected for each elevatorcar, and said second interval detecting means detects the time intervalwhich is the sum of the spatial distance between each elevator car andthe succeeding elevator car and the time distance related to the numberof stoppages expected for the succeeding elevator car.
 14. An elevatorcontrol system for controlling at least three elevator cars servicing aplurality of service floor landings comprising: car detecting meansprovided for each elevator car to detect the nearest car to eachelevator car among the elevator cars which follow each elevator car,interval detecting means provided for each elevator car to detect theinterval between each elevator car and the nearest one to said eachelevator car, comparator means provided for each car to compare theinterval detected by the interval detecting means provided for eachelevator car with the interval detected by the different intervaldetecting means provided for a different elevator car and to produce anoutput signal when said last-mentioned interval exceeds by apredetermined value said first-mentioned interval, and means responsiveto the output signal of said comparator means for preventing theelevator car associated with said comparator means from responding tohall calls.
 15. An elevator control system for controlling at leastthree elevator cars servicing a plurality of floor landings comprising:car detecting means provided for each elevator car to detect the nearestcar to each elevator car among the elevator cars which are in advance ofsaid elevator car, interval detecting means provided for each elevatorcar to detect the interval between said each elevator car and thenearest car to each elevator car, comparator means provided for each carto compare the interval detected by the interval detecting meansprovided for each elevator car with the interval detected by thedifferent interval detecting means provided for a different elevator carand to produce an output signal when said first-mentioned intervalexceeds by a predetermined value said last-mentioned interval, and meansresponsive to the output signal of said comparator means for preventingthe elevator car associated with said comparator means from respondingto hall calls.